* {
  margin: 0;
  padding: 0;
}
body {
  font-family: "Titillium Web", "Helvetica Neue", "Helvetica", Arial, sans-serif;
  background-color: black;
}
.header {
  width: 100%;
  padding-top: 21px;
}
.nav {
  width: 1366px;
  height: 124px;
  margin: 0 auto;
  position: sticky;
  top: 0;
  z-index: 100;
  background:url(https://www.nasa.gov/sites/all/themes/custom/nasatwo/images/starfield-banner.jpg);

}
.nav > a > img {
  margin-top: 20px;
  width: 110px;
  height: 92px;
  float: left;
}
.menu {
  width: 826.95px;
  height: 80px;
  line-height: 80px;
  position: absolute;
  left: 255px;
  font-size: 1.25em;
  color: #fff;
  font-family: "Titillium Web", "Helvetica Neue", "Helvetica", Arial, sans-serif;
  display: flex;
  justify-content: stretch;
  cursor: pointer;
}
.menu::after {
  content: "";
  display: inline-block;
  height: 60%;
  width: 1px;
  position: absolute;
}
.menu > li:nth-child(even) {
  width: 1.4px;
  height: 60%; 
  margin-top: 15px;
  background-color: rgb(85,85,85);
}
.menu > li:nth-child(odd) {
  flex: auto;
  padding: 0 10px;
  position: relative;
  
}
.menu > li:nth-child(odd):hover {
  background-color: rgb(21, 65, 139);
  display: block;
}

.footer {
  position: absolute;
  width: 1100px;
  height: 40px;
  background-color: rgb(85, 85, 85);
  text-decoration: none;
  color: #fff;
  font-size: 15px;
  margin: 84px 168px;
  display: flex;
  justify-content: stretch;
}
.footer::after {
  content: "";
  display: inline-block;
  width: 1px;
  position: absolute;
}
.footer li:nth-child(even) {
  width: 1.4px;
  height: 60%;
  background-color: #888;
  margin-top: 8px;
}
.footer li:nth-child(odd):hover {
  background-color: #888;
  cursor: pointer;
}
.footer li:nth-child(odd) {
  padding: 0 10px;
  flex: auto;
  position: relative;
  line-height: 40px;
}
li {
  list-style: none;
  display: inline-block;
}
.search {
  width: 159px;
  height: 39px;
  background-color: #333333;
  position: absolute;
  right: 95px;
  top: 25px;
  color: rgb(85, 85, 85);
  padding-left:5px;
  border: none;
}
.icon-RectangleCopy {
  font-size: 25px;
  position: absolute;
  right: 103px;
  top: 30px;
  color: #fff;
}
.icon-weibiaoti- {
  font-size: 25px;
  position: absolute;
  right: 50px;
  top: 30px;
  color: #fff;
}
.box {
  height: 1800px;
  width: 1366px;
  margin: 0 auto;
  padding-top: 10px;
}
.box_one {
  height: 674.5px;
  width: 660px;
  float: left;
  position: relative;
}
.box_Footer {
  position: absolute;
  font-size: 20px;
  line-height: 28px;
  color: #fff;
  background: #5d7fb9;
  padding: 6px 12px;
  z-index: 10;
  bottom: 34px;
  width: 182px;
  height: 28px;
  opacity: 0.85;
}
.box :hover.box_Footer {
  opacity: 1;
  cursor: pointer;
}
.box :hover.box_Footer_top {
  opacity: 1;
  cursor: pointer;
}
.box_Footer_top {
  position: absolute;
  font-size: 20px;
  line-height: 28px;
  color: #fff;
  background: #5d7fb9;
  padding: 6px 12px;
  z-index: 10;
  bottom: 46px;
  width: 182px;
  height: 28px;
  opacity: 0.85;
}
.box_Footer1 {
  font-weight: 600;
  padding-left: 12px;
  box-sizing: border-box;
  font-size: 18px;
  line-height: 34px;
  color: #000;
  background-color: rgb(221, 220, 216);
  height: 34px;
  width: 100%;
  position: absolute;
  bottom: 0;
  z-index: 10;
  opacity: 0.85;
}
.box_Footer2 {
  font-weight: 600;
  padding-left: 12px;
  box-sizing: border-box;
  font-size: 18px;
  line-height: 23px;
  color: #000;
  background-color: rgb(221, 220, 216);
  height: 46px;
  width: 100%;
  position: absolute;
  bottom: 0;
  z-index: 10;
  opacity: 0.85;
  word-wrap: break-word;
  text-overflow: ellipsis;
}
.box :hover.box_Footer2 {
  cursor: pointer;
  opacity: 1;
}
.box :hover.box_Footer1 {
  cursor: pointer;
  opacity: 1;
}
.box_two {
  height: 674.5px;
  width: 690px;
  float: right;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
}
.box_two_1 {
  width: 340px;
  height: 315px;
  position: relative;
  background-color: rgb(34, 34, 34);
  position: relative;
}

.box_two .box_two_1 > img {
  position: absolute;
  left: 50%;
  top: 50%;
  margin: -30px -45px;
  cursor: pointer;
}
.box_two_2 {
  width: 340px;
  height: 315px;
  background-color: rgb(57, 113, 158);
  position: relative;
}
.box_two_2 .title > a:hover {
  text-decoration: underline;
  cursor: pointer;
}
.box_two_3 {
  width: 690px;
  height: 330px;
  margin-top: 25px;
  position: relative;
}
.box_three {
  margin-top: 10px;
  height: 330px;
  width: 100%;
  float: left;
  display: flex;
  justify-content: space-between;
}
.box_three_1 {
  width: 330px;
  position: relative;
}
.box_three_2 {
  width: 675px;
  position: relative;
}
.box_three_3 {
  width: 330px;
  background-color: black;
  position: relative;
}
.box_four {
  height: 300px;
  width: 100%;
  display: flex;
  justify-content: space-between;
  float: left;
  margin-top: 15px;
}
.box_four_1 {
  width: 330px;
  position: relative;
}
.box_four_2 {
  width: 330px;
  position: relative;
}
.box_four_3 {
  width: 330px;
  position: relative;
}
.box_four_4 {
  width: 330px;
  position: relative;
}
.box_five {
  width: 100%;
  height: 40px;
  margin-top: 25px;
  float: left;
  text-align: center;
  line-height: 40px;
  color: #fff;
  background: #15418c;
  cursor: pointer;
  font-size: 17px;
  font-weight: 600;
}
.box_five:hover {
  background: #5d7fb9;
}

.no-countdown {
  border-bottom: 1px solid #fff;
  margin: 0 auto 3px;
  width: 96%;
  padding: 8px 0 6px 0;
  font-size: 14px;
  font-weight: 500;
  color: #fff;
  line-height: 1.1;
}
.title {
  padding-top: 2px;
  padding-bottom: 0.2em;
  color: #fff;
  padding-left: 4px;
  font-size: 14px;
}
.event-bottom {
  border-top: 1px solid #fff;
  position: absolute;
  bottom: 0;
  left: 2%;
  width: 96%;
  background-color: #39719e;
  text-align: center;
  text-decoration: none;
  color: #fff;
  font-size: 12px;
}
.event-bottom span:nth-child(1) {
  float: left;
  width: 40%;
}
.event-bottom span:nth-child(2) {
  float: right;
  width: 50%;
}
.box_six {
  width: 100%;
  height: 300px;
  float: left;
  position: relative;
  color: #fff;
  font-size: 14px;
}
.box_six > img {
  position: absolute;
  top: 20px;
}
.span1 {
  top: 30px;
  left: 95px;
  position: absolute;
}
.span2 {
  top: 45px;
  left: 95px;
  position: absolute;
}
.box_Six_Footer {
  width: 960px;
  height: 40px;
  position: absolute;
  top: 115px;
  right: 0px;
  display: flex;
  justify-content: space-between;
  margin-right: 10px;
  color: #5d7fb9;
  font-size: 13px;
}
 .box_Six_Footer>li:hover{
  text-decoration: underline;
  cursor: pointer;
}
.dropdown1 {
  display: none;
  position: absolute;
  left: 0px;
  background-color: rgb(21, 65, 139);
  padding:5px 0;
  line-height:30px;
  
}
.dropdown1 > li {
  cursor: pointer;
  font-size: 16px;
  padding: 5px 10px;
  white-space: nowrap;
  box-sizing: border-box;
  display: block;
}
.menu li:hover .dropdown1 {
  display: block;
  z-index: 200;
}
 .menu ul li:hover{
  background-color: #072F54;
  width: 100%;
}
